iOS Keyboard show & hide tricks

Almost all app needs text input function, means all need to handle the keyboard show and hide issues.

My rough idea is as below steps:

1, adding an outlet of bottom constraint to the view that you want to scroll up when keyboard shows or hides.

    @IBOutlet weak var bottomConstraint: NSLayoutConstraint!

2, setting up to get keyboard show or hide notifications

    override func viewWillAppear(_ animated: Bool) {
        NotificationCenter.default.addObserver(self, selector:#selector(keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        NotificationCenter.default.removeObserver(self)
    }

3, handling when notification fired.

    func keyboardWillShow(notification:Notification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
            self.bottomConstraint.constant = keyboardSize.height
        }
    }
    
    func keyboardWillHide(notification:Notification) {
        self.bottomConstraint.constant = 0
    }

just that simple